<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    
  </style>
</head>
<body>
  <div id="app">
    <button @click="createMsg">动态创建msg</button>
    <div v-if="isShow">
      <button @click="changeMsg">修改msg</button>
      {{msg}}
    </div>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue@2.7.14/dist/vue.js"></script>
  <script>
    const vm = new Vue({
      data: {
        isShow: false
      },
      methods: {
        createMsg(){
          this.msg = '你好世界';
          this.isShow = true
        },
        changeMsg(){
          this.msg = '值改变了'
          console.log(this.msg);
        }
      }
    })

    vm.$mount('#app')
  </script>
</body>
</html>